Electromagnetic door holder

ABSTRACT

An electromagnetic door holder comprising a wall-mounted electromagnet and a door-mounted armature portion. The armature portion includes a pivotally supported armature element capable of being moved in substantially any direction on a supporting plate which is adapted for mounting upon the door. The armature element includes an apertured flange, and the door-mounted support plate includes a bifurcated portion for receiving the flange, with a fastening bolt passing through aligned apertures in the opposing leg elements of the bifurcated portion. A pair of nylon bushings is employed, one on either side of the aperture in the flange, and each of the bushings has a generally spherical outer configuration enabling it to be pivotally supported between a respective one of the bifurcated portions and a screw-adjusted retaining means. The frictional resistance to movement of the armature element may be adjusted by the screw so that it will tend to retain the position to which it is last moved, thereby permitting adjustment of the armature element in such manner as to lie perfectly flush against the electromagnet.

United States Patent [191 Larime [4 Oct. 21, 1975 ELECTROMAGNETIC DOOR HOLDER Carl M. Larime, Fairfield, Conn.

[73] Assignee: General Signal Corporation,

Rochester, NY.

22 Filed: Jan. 25, 1974 21 Appl. No.: 436,774

[75] Inventor:

Primary ExaminerRichard E. Moore Attorney, Agent, or FirmPollock, Philpitt & Vande Sande [57] ABSTRACT An electromagnetic door holder comprising a wallmounted electromagnet and a door-mounted armature portion. The armature portion includes a pivotally supported armature element capable of being moved in substantially any direction on a supporting plate which is adapted for mounting upon the door. The armature element includes an apertured flange, and the door-mounted support plate includes a bifurcated portion for receiving the flange, with a fastening bolt passing through aligned apertures in the opposing leg elements of the bifurcated portion. A pair of nylon bushings is employed, one on either side of the aperture in the flange, and each of the bushings has a generally spherical outer configuration enabling it to be pivotally supported between a respective one of the bifurcated portions and a screw-adjusted retaining means. The frictional resistance to movement of the armature element may be adjusted by the screw so that it will tend to retain the position to which it is last moved, thereby permitting adjustment of the armature element in such manner as to lie perfectly flush against the electromagnet.

4 Claims, 5 Drawing Figures m SUPPLY 1 e LOCATIONS a a w FIRE DETECTION SYSTEM US. Patent Oct. 21, 1975 TO OTHER LOCATIONS aggggg ELECTROMAGNET /22 POWER SUPPLY ELECTROMAGNETIC DOOR HOLDER BACKGROUND OF THE INVENTION It is well-known in the art to provide automatic door closure systems for public buildings whereby fire doors interconnecting various parts of a building are normally in the open position and retained in that position by means of an electromagnetic device comprising a wallmounted electromagnet and an armature means for the electromagnet which is mounted on the door. With the door in the open position, the armature element on the door is brought into juxtaposition with the electromagnet on the wall, and the door is held open as long as the electromagnet remains energized. In the event of a fire, for example, the electromagnets for the various doors can be selectively or all de-energized, thereby permitting the corresponding doors to swing shut by means of associated door closure means.

It is necessary, of course, that the door, when held in the open position, provide for the armature element to be brought into a position where it is exactly flush with an element forming a part of the wall-mounted electromagnet. Often this is accomplished by providing that the armature element itself be, in effect, loosely supported on a mounting bracket secured to the door. As a result, whenever the door is opened, the armature element is brought into physical contact with the electromagnet, and the loose fitting of the armature element upon its associated mounting bracket then permits it to assume a position where it is flush with the associated element on the wall. It has been found, however, that the manufacture of such devices entails a considerable amount of cost, resulting principally from the difficulty of properly assembling the various elements so as to provide the desired degree of freedom of the armature element relative to its supporting bracket.

SUMMARY OF THE INVENTION It is the object of the present invention to provide a door-mounted armature means for an electromagnetic door closure apparatus comprising a door-mounted bracket and with a pivotally mounted armature element secured thereto. The securing means for the armature element comprises a flange on the armature element defining therein an aperture and a bifurcated portion on the door-mounted bracket capable of receiving the flange between the opposing legs of the bifurcated portion. The distance between the opposing faces of the leg portions of the bifurcated portion is substantially greater than the thickness of the flange so that the leg portions do not restrict the freedom of movement of the armature element.

The fastening means for the armature element comprises a threaded bolt passing through aligned apertures in the opposing legs of the bifurcated portion and with such bolt passing through the aperture in the flange comprising a part of the magnet armature. A pair of nylon bushing elements each having a generally hemispherical outer surface is provided to permit a substantial degree of freedom of movement of the armature element while yet permitting adjustment of the frictional resistance so that the armature element will retain the position to whichrit is last operated and thereby maintain its flat outer surface perfectly flush against the wall-mounted electromagnet.

BRIEF DESCRIPTION OF THE DRAWINGS In describing the invention, reference will be made to the accompanying drawing in which:

FIG. 1 diagrammatically illustrates an electromagnetic door system employing the door-mounted armature means of the present invention;

FIG. 2 illustrates in perspective form the doormounted armature means of the present invention and also the wallmounted electromagnet;

FIG. 3 illustrates in perspective the several elements comprising the door-mounted armature means;

FIG. 4 is a plan view of the armature means of this invention; and

FIG. 5 is a side view of the apparatus of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 comprises a diagrammatic illustration of an electromagnetic system for the control of various doors in a building. A plurality of doors 10 is shown, each provided with a closure means 12 normally acting to urge each door 10 to a closed position with respect to the door frame provided in wall 14. Mounted on each door 10 is a magnet armature means 16 which is in juxtaposition with an electromagnet means 18 securely mounted to wall 20. A power supply 22 provides energization over wires 24 for normally energizing each of the electromagnet means 18 to thereby retain each door 10 in the open position. However, in the event of the detection of, for example, a fire by the fire detection system 26, the power supply 22 de-energizes wires 24, thereby releasing electromagnet means 18 so that each door can then be swung to its closed position.

The wall-mounted electromagnet means of the invention is shown at 26 in FIG. 2. This electromagnet means 26 is provided with a flat circular outer surface forming opposed magnetic poles 28 and 29 of an electromagnetic circuit. The door-mounted armature means of the invention is also shown in FIG. 2 and comprises a mounting bracket 30 as well as an armature element 32.

FIG. 3 illustrates in greater detail the door-mounted bracket 30 as comprising a bifurcated portion including two opposed leg portions 32 and 34. Both of the leg portions define axially aligned through bores 36 and 38 respectively, the upper bore 36 being threaded so as to threadably engage with the threaded end of a bolt 40 which can be inserted into the aligned apertures by passing such bolt together with the cooperating nut 42 upwardly through the bottom of bore 38 and then screwing the bolt 40 into the threaded aperture 36. The nut 42 is provided with a central aperture therein which is sufficiently large so as to be slidable along the shaft of bolt 40. Thus, preferably the nut 42 does not have internal threads engaging with the threaded end of bolt 40 but is rather readily slidable along the bolt.

The armature element 32 is provided with a flange portion 44 having a cylindrical aperture 46 formed therein. The diameter of this aperture 46 is slightly in excess of that of the cylindrical portion 48 of each bushing 50. In addition to having the cylindrical portion 48, each bushing is provided with a generally hemispherical outer surface 52 and also defines a central bore 54 therethrough which is tapered as shown in the cross-sectional view of FIG. 5, having a diameter at its cylindrical end which is only slightly larger than the diameter of bolt 40 but having a significantly larger diameter at its other hemispherical end.

The assembly of the various parts of the armature means is shown in FIGS. 4 and 5. To assemble the mechanism, the two bushings 50 are inserted into opposite sides of the aperture 46 in flange 44, and this assembly is then placed between the two opposed legs 32 and 34. Thereafter, the nut 42 is placed upon bolt 40, and this combination of elements is inserted into the aperture 38 from below and with the threaded end of bolt 40 then screwed into the threads of aperture 36. As the bolt is threaded further into the threaded aperture 36, greater pressure is exerted by the upper end of nut 42 against the lower one of the bushings 50 so that both of these bushings are squeezed together and the frictional resistance to movement of flange 44 is thereby increased. The tapered diameter of the bushings 50 permits a substantial degree of movement of armature element 32 about an axis at right angles to bolt 40, and of course there is an even greater degree of freedom of movement of armature element 32 about the axis of bolt 40 as is more clearly illustrated in FIG. 4.

It will thus be apparent that the present invention provides a means whereby an armature element may be adjusted to any desired position and yet be frictionally restrained from moving from that position once adjusted. This adjustability is provided by a very simple arrangement of parts which facilitates their convenient and quick assembly.

What I claim is:

1. In an electromagnetic door holder for retaining a door in an open position and being of the type which comprises an electromagnetic flux generating means and an armature one of which is secured to the door while the other is disposed at a selected position, the improvement comprising:

said armature means comprising a bracket and an armature element supported on said bracket by a pivotal support means,

said pivotal support means including a bifurcated portion having axially aligned apertures in its opposed leg portions and also including an apertured flange disposed between said leg portions,

a bolt passing through said aligned apertures and means for adjusting the position of said bolt axially relative to said opposed leg portions,

a pair of bushings each having at least in part a generally spherical portion and respectively disposed on opposite sides of said flange,

each bushing being secured to one of said two members while its part spherical portion bears against and rotates relative to the other said member to permit thereby substantially unrestricted rotation of said flange in any direction relative to said bracket over at least a predetermined range of motion,

said bolt adjusting means comprising a threaded end portion of said bolt which threadably engages with one of said opposed leg portions and further including means on said bolt which is forcibly urged against one of said bushings as said bolt is threaded into said one opposed leg portion, said bolt adjusting means controlling the frictional restraining force exerted between said flange and said opposed leg portions through said bushings.

2. In an electromagnetic door holder for retaining a door in an open position and being of the type which comprises an electromagnetic flux generating means and an armature one of which is secured to the door while the other is disposed at a selected position, the improvement comprising:

said armature means comprising a bracket and an armature element supported on said bracket by a pivotal support means,

said pivotal support means including a bifurcated portion having axially aligned apertures in its opposed leg portions and also including an apertured flange disposed between said leg portions,

a pair of apertured bushings each having at least in part a generally spherical portion, said bushings contacting said flange on opposite sides thereof and with one of said bushings being urged against a respective one of said opposed leg portions,

bolt means passing through said aligned apertures and through the aperture in said bushings for adjustably compressing said bushings and said flange between at least one of said leg portions and a means responsive to axial adjustment of said bolt means for adjusting the frictional resistance to rotation of said flange relative to said bracket,

said part spherical portions on said bushings permitting substantially unrestricted rotation of said flange in any direction relative to said bracket and to said bolt over at least a predetermined range of motion.

3. The improvement of claim 2 wherein said bifurcated portion is integral with said bracket and said flange is integral with said armature element.

4. The improvement of claim 2 wherein each said bushing includes a cylindrical portion fitting within said aperture in said flange and said generally spherical portion extending outwardly on each side of said flange, at least one of said spherical portions bearing against a respective one of said opposed leg portions. 

1. In an electromagnetic door holder for retaining a door in an open position and being of the type which comprises an electromagnetic flux generating means and an armature one of which is secured to the door while the other is disposed at a selected position, the improvement comprising: said armature means comprising a bracket and an armature element supported on said bracket by a pivotal support means, said pivotal support means including a bifurcated portion having axially aligned apertures in its opposed leg portions and also including an apertured flange disposed between said leg portions, a bolt passing through said aligned apertures and means for adjusting the position of said bolt axially relative to said opposed leg portions, a pair of bushings each having at least in part a generally spherical portion and respectively disposed on opposite sides of said flange, each bushing being secured to one of said two members while its part spherical portion bears against and rotates relative to the other said member to permit thereby substantially unrestricted rotation of said flange in any direction relative to said bracket over at least a predetermined range of motion, said bolt adjusting means comprising a threaded end portion of said bolt which threadably engages with one of said opposed leg portions and further including means on said bolt which is forcibly urged against one of said bushings as said bolt is threaded into said one opposed leg portion, said bolt adjusting means controlling the frictional restraining force exerted between said flange and said opposed leg portions through said bushings.
 2. In an electromagnetic door holder for retaining a door in an open position and being of the type which comprises an electromagnetic flux generating means and an armature one of which is secured to the door while the other is disposed at a selected position, the improvement comprising: said armature means comprising a bracket and an armature element supported on said bracket by a pivotal support means, said pivotal support means including a bifurcated portion having axially aligned apertures in its opposed leg portions and also including an apertured flange disposed between said leg portions, a pair of apertured bushIngs each having at least in part a generally spherical portion, said bushings contacting said flange on opposite sides thereof and with one of said bushings being urged against a respective one of said opposed leg portions, bolt means passing through said aligned apertures and through the aperture in said bushings for adjustably compressing said bushings and said flange between at least one of said leg portions and a means responsive to axial adjustment of said bolt means for adjusting the frictional resistance to rotation of said flange relative to said bracket, said part spherical portions on said bushings permitting substantially unrestricted rotation of said flange in any direction relative to said bracket and to said bolt over at least a predetermined range of motion.
 3. The improvement of claim 2 wherein said bifurcated portion is integral with said bracket and said flange is integral with said armature element.
 4. The improvement of claim 2 wherein each said bushing includes a cylindrical portion fitting within said aperture in said flange and said generally spherical portion extending outwardly on each side of said flange, at least one of said spherical portions bearing against a respective one of said opposed leg portions. 